Modification of hydroxyl containing polyvinyl resin treated with an amino acetal as a silver halide binder



n d SmsP w I N. Y., assignors to Eastman Kodakconipany, Rochester, N.Y., a corporation of. New; Jersey N0 Drawing. Application August 12,1952, Serial; No. 303395 2 Claims. 11. 95-7 This invention relates to aprocess and, product in volving modification of a hydroXy-l-containingpolyvinyl resin such as polyvinyl alcohol or a substantially bydrolyzedpolyvinyl acetate by treatment, with an amino acetal, the resultapparently being the. introduction of substitucnt amino groups attachedto the polyvinyl compound through cyclic acetal linkages. The modifiedpolymers are particularly useful in applications where gelatin haspreviously been used, such as in carriers for light sensitive substancesin the photographic art.

It is known that vinyl acetate polymerized to polyvinyl acetate may behydrolyzed "topolyvinyl alcohol'which may be used an an intermediate informing various polyvinyl resins; Some of these resins have gelatin likequalities and may besubstitutedfor gelatin as a carrier for.light-sensitive silversalts and e lkein photographic film. One of thesere's'iris, whic n aflinity foracid 2,739,059 I Pa en ed. Mer- 2.0,v1956.

It is, accordingly, an object of our invention to provide a new processand product involving the treatment of a hydroxyl containing polyvinylresin such as polyvinyl alcohol or hydrolyzedpolyvinyl acetate with anamino acetal. A further object of the invention is to provide a gelatinsubstitute which may be used in the photographic and other arts, as formaking a photographic emulsion containing light-sensitive material suchas silver salts. Another object is to provide a new photographic elementcomprising a gel made. up of amino acetal treated polyvinyl alcohol orhydrolyzed, polyvinyl acetate and carrying a light-sensitive substance.Another. obiect of the invention is to provide a tough clear transparentfilm which may be readily hardened or rendered less water susceptible.

In accordance with our invention, we prepare our new class of p y rs ymo ify ng. a hydroxy c ntaining polyvinyl resin such as polyvinylalcohol or a substantially hydrolyzedpolyvinyl acetate by treatment withan amino acetal, which apparently results in the introduction ofsubstituent amino groups. The reaction is preferably carried out inwater under acid conditions wherew dtthe hydroxyl groups on thep y nr cl r up m nvertedby r action withth am noacetal.

ifinefofr the amino acetals whichrnay be employeglto dyestuffs, can beformed bythe' actio'iiofa halogenalkyl "th cntiq .-v 1 and, th' l i itymay b s1Witnin'ccttamlimit .exec i ely high'temperatures, say in theraii'gof 100? C. 'anda 'ov'e amine, for example, bromethylamine onpolyvinyl alcohol. Another which can be I used to provide photographicelements with layers composed of gelled hydroxyl polymer compounds isproduced .by treating the polyvinyl alcohol with'a'n aqueous solutioncontaining an acylacetamide.

We have now found that a new resinous polymer is formed by modifying ahydroxyl containing polyvinyl resin such as polyvinyl alcohol orsubstantially hydrolyzed polyvinyl acetate by treatment with an aminoacetal, which apparently results in the introduction of substituentamino groups. By amino acetal is meant an acetal formed by the reactionof an amino aldehyde with an alcohol. The amino groups are thought to beattached to the polyvinyl alcohol through cyclic acetal linkages. Unlikeunmodified polyvinyl alcohol, the products obtained according to thisinvention are capable of being hardened or rendered less watersusceptible by treatment with a variety of substances such as aldehydes(e. g., formaldehyde), customarily used as tanning agents forwater-soluble proteins such as gelatin. They may likewise be mixed withpolyvinyl alcohol not containing amino groups and the whole compositionhardened by" treatment with aldehydes and like substances. Compounds ormaterials capable of liberating formaldehyde or an additive orderivative compound or polymer of formaldehyde, capable of beingdissolved to form a hardening solution may be used. Examples of suchcompounds are formaldehyde bisulfite, hexarnethylene tetramine,trioxymethylene, paraform, paraformaldehyde, and polyoxymethylene. Ifthe gelatin hardening solution is to be compounded for immediate userather thanbeing packaged for future'use, liquid hardening agents,

such as acetyl benzoyl, acetyl caproyl, diacetyl, dibenzoyl,acetaldchyde, 2,3-butanedione, dichloroacetone, diketoachieve theobjectives of this invention is g-amino' diethyl a etal. but this. ismet j t suc C mp und when a.

is th ar i c-s s .lead to poor color in the polymer, presumably due toside reactions not important at'lower temperatures.

The following examples are given 'merely in an illusltrative sense andthe invention is not to bev considered as restricted thereto.

ExampIeM0dificoti0n of polyvinyl alcohol by fi-amin'o diethyl acetalSeventeen parts of polyvinyl alcohol made from polyvinyl acetate havinga viscosity of 22 centipoises/molar solution with benzene, weredissolved in 158 parts water. To this were added parts l-Normalhydrochloric acid, and 5.26 parts ,B-amino diethyl acetal. Afterwithdrawal of a portion of the reaction mixture as a control, thebalance was heated at 58 C; Samples were withdrawn for analysis atvarious times thereafter. The polymers in these samples were isolated byprecipitation in ethyl alcohol followed by redissolution in water and asecond precipitation in acetone. Known weights of the products weretitrated electrometrically to determine the amount of amino nitrogen andtotal nitrogen was determined by elemental analysis. The following tableshows the results of the analyses:

f Time of Percent Y Percent Sample High? at 1 -3 3 (wt) N (Hrs) ftitration (total) I 0 14: 2 2% 225 2 i 36 3 3 60 5 24 i590 1 0 48 ll 171 2 The solubility of the polymers obtained became progressively greaterin organic solvents such as alcohols as the N content increased.

Although we do not wish to be bound by any theory of ept se tativ ofthe, class operation of the invention, we believe that takes place asfollows:

Hr-NHzPICH where CHOH-CHa-CHOH-CH2 a portion of a long chain polyvinylalcohol.

The following example illustrates how a polyvinyl alcohol partiallysubstituted with amino acetal groups may be rendered insoluble in waterat elevated temperatures.

A partial amino acetal of polyvinyl alcohol of the type disclosed inExample 1 containing .6% amino nitrogen was dissolved in water to make a5% (wt.) solution. Twenty parts of this solution were mixed with onepart of 5% formaldehyde. The mixture was adjusted to pH 7 with dilutesodium hydroxide and one part of a buffer at pH 7 was added. Thiscomposition was coated in a thin film on a glass plate. After drying andcuring, at room temperature for two and one-half days, the resultantrepresents foil was not dissolved or disintegrated by water at 100 C.

The polyvinyl resins prepared in accordance with our invention arevaluable substitutes for gelatin in the production of photographicemulsions and films. Tough, homogeneous films can be provided which areuseful for example, as carriers for light-sensitive materials such as Isilver salts. Gelatin used widely in the prior art for this purpose isobtained'ijrom animalmatter and, is subject to variation in its chemicalcomposition. Consequently,

great care and expense must be invested to purify gelatin used in thephotographic art as in emulsions to avoid deleterious effects on thetlight sensitive materials used therewith. Use of the compositions wehave invented provides greater control over the carrier of the lightsensitive material and enables production of film at a lower cost. Forthis reason, our invention has great utility and special advantage inthe photographic industry. However, it also provides resins useful inother arts requiring substances having the properties of our modifiedpolyvinyl polymers.

We claim as our invention:

1. A photographic element comprising polyvinyl alcohol modified byreacting with fi-amino diethyl acetal and containing a light-sensitivesilver halide salt.

2. A process for forming a photographic element comprising modifyingpolyvinyl alcohol by dissolving the polyvinyl alcohol in water,adjusting this solution to a pH of about 0.7 by the addition ofhydrochloric acid, and subjecting the solution to prolonged heating withfi-amino diethyl acetal at a temperature below about C. and adding tothe resulting modified polyvinyl alcohol light-sensitive silver halidesalts.

References Cited in the file of this patent UNITED STATES PATENTS

1. A PHOTOGRAPHIC ELEMENT COMPRISING POLYVINYL ALCOHOL MODIFIED BYREACTING WITH B-AMINO DIETHYL ACETAL AND CONTAINING A LIGHT-SENSITIVESILVER HALIDE SALT.